1. Field of the Invention
This invention relates to a hand and digit immobilizer for preventing a patient from dislodging a pulse oximeter finger sensor by finger movement or fist clenching.
2. Description of the Related Art
Pulse oximetry is used in the medical profession for monitoring the oxygenation of patients during surgical procedures under general anesthesia, during outpatient and office based anesthetics, recovery room, emergency room, intensive care and ambulance environments. In typical pulse oximetry, use is made of a finger sensor into which is integrated at least one light source, such as a light emitting diode, on the emission side of the sensor and at least one photoreceiver which is located on the opposite reception side of the sensor. The light emitted by the light source is introduced into the tissue of the patient to be monitored and the photoreceiver measures the intensity of the light transmitted through the tissue. The intensity measured on the reception side can be used for calculating the oxygen saturation in the arterial blood of a patient.
FIG. 1 shows one example pulse oximetry sensor as described in U.S. Pat. No. 5,776,059. The sensor 10 has a first casing section 12 that houses the light source 14. During application, the sensor 10 is placed on a finger 16 of a patient and is fixed there with an adhesive. A second casing section 18 with elastic properties passes around the finger 16 and thus ensures mechanical fixing. The second casing section 18 includes the photoreceiver 22 which measures the intensity of the light radiated through the human finger tissue. The photoreceiver 22 is electrically connected to an electrical cable 24 that is connected to a processor and monitor where electrical signals are processed and measurements are displayed. An example processing circuit used in pulse oximetry is described in U.S. Pat. No. 5,934,277. It is noted that U.S. Pat. No. 5,776,059 shows one example finger sensor; however, finger sensors that use a clip type structure are also well known. See, for example, U.S. Pat. Nos. 6,505,061 and 6,154,667.
While existing pulse oximetry finger sensors are suitable for many applications, they do have drawbacks. Namely, involuntary patient movement can dislodge finger sensors. For example, fist clenching, finger movement, and fidgeting with the finger sensor will often dislodge or even break pulse oximetry finger sensors. This results in false readings, motion artifact, and wasted time during surgery or the particular monitoring event by the necessity of constant replication or adjustment of the finger sensor. Additionally, broken finger sensors can be costly to replace.
Accordingly, there is a need for a means for preventing a patient from dislodging a finger sensor by finger movement or fist clenching. Such a device should be safe, easy to apply and remove, be disposable depending on environment, while holding the hand and fingers safely in a neutral position without compression of the skin or underlying nervous or vascular structures.